I' m running with stock coils on a 71 750 with 41k on the speedo. I think I want to put on some new coils and wires. The battery I have now has been good for 3.5 yrs. I always run with the headlight on, I also have a Dyna 2 ign. If I go with 3 ohm coils what might be the life on my battery ? Just interested or would you go with the 5 ohms ?